Pneumatic hammer.



LP. A. OTTO.

PNEUMATIC HAMMER;

APPLIOATION FILED JAN. 8, 1910.

973,378, Patented Oct. 18,1910.

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FRIEDRICH ABOLF OTTO, OF REMSCI-IEID, GERMANY, ASSIGNOR TO COMPANY ALEX- ANDERWERK A. VONDEB NAHMER AKTIEN-GESELLSCI-IAFT, 9F REMSCHEID, GER- MANY.

PNEUMATIC HAMMER.

Specification of Letters Patent.

Patented Oct. 18, 1910.

To all whom it may concern:

Be it known that I, FRIEDRICH AnoLr' O'rro, engineer, a citizen of the German Empire, and resident of n Freiheitstrasse, Itemscheid, in the German Empire, have invented certain new and useful Improvements in Pneumatic Hammers and the Like, of which the following is a specification.

This invention relates to improved means for effecting the distribution of the operating medium (air) in pneumatic hammers and its object is to so form the air distributing organs that the greatest efliciency is obtained while only a small quantity of the working fluid is used and all resistances in front of and to the rear of the piston are avoided.

The invention is particularly applicable to rock drills having automatic reversing gears as in such devices the piston stroke must be retained within narrow limits owing to the nature of the reversing mechanism and the necessity of keeping the weight of the parts as small as possible.

The invention is illustrated by way of example in the accompanying drawings, in which:

Figure 1 is a vertical section showing the position of the distributing valve after the piston has completed its working stroke. Fig. 2 is a section at right angles to that shown in Fig. 1 and illustrates the position of the parts at the end of the return stroke and beginning of the working stroke. Fig. 3 shows the striking piston or tup and the distributing valve in the same positions as Fig. 2 but as applied to a modified form of admission gear for the working stroke of the tup.

In carrying the invention into effect according to the form shown in Figs. 1 and 2, the distributing valve cl is arranged as a stepped piston valve in which the smaller upper surface is constantly under pressure, being connected to the pressure fluid supply 9 by means of the passage h and recessed part 2'. In this way as shall be described later, the movement of the striking part of the piston is assured for any position of the same in either its working or return stroke.

Referring further to the construction of the stepped piston valve (Z and more par ticularly to the relative areas of the end surfaces thereof, it will be observed that the body of this valve is formed with end surfaces of different areas, the smaller of which end surfaces has the inner edges exposed constantly to the pressure existing in the recessed part '2 Furthermore, it will be noted that the valve d is arranged to operate within a valve seat member C within the valve casing c and having interior spaces and passages providing the communication heretofore pointed out.

The device operates as follows :IVhen the piston 22 has reached its lowest position, shown in Fig. 1, and after the pressure fluid has expanded as much as possible and the piston has closed the supply passage' the pressure fluid beneath the step of greater diameter of the piston valve has passed back into the expansion space of the cylinder behind the tup b after the port or passage 8 (see Fig. 2) has been uncovered. In the space below the greater surface of the piston valve d there results a considerable reduction in pressure and the valve will in consequence be moved downward from the posit1on shown in Fig. 2 to that shown in Fig. 1 by the pressure acting continually on the smaller surface of the piston. In this lower position the working fluid passes from the supply 9 through the passage h, bored out part i, annular groove and passage Z to the bottom of the piston 72 and thereby effects the return motion of the piston 71. At the same time the cylinder space a above the tup or piston b is connected to the exhaust 39 through the passage m and annular grooves and 0. The expanded fluid passes thereby into the atmosphere and no resistance is offered to the tup or piston b during its return stroke. In the return movement of the tup or piston b as soon as the upper edge of the annular groove reaches the pressure fluid supply 9 (Fig. 2), the port 9 is uncovered and the pressure fluid passes through the port or passage 9 to the greater surface of the distributing valve 03 and thereby presses this valve upward to the position shown in Fig. 2. The space beneath the piston b is, in this position of the valve, placed in communication with the exhaust p through the piston b completes its stroke due to the expansion of the working fluid. The valve (1 is again pressed downward when the working stroke is completed, owing to the difference of the pressures on top and bottom of the valve. The working stroke is then repeated. The pressure fluid under the valve d passes, as described above, back through the port 5 into the cylinder when the valve d moves downward.

In Fig. 3 there is illustrated a similar distributing device but in this case the pressure fluid supply for the working stroke of the tup or piston 6 takes place through passages in the working cylinder a I wish it to be understood that the expressions upper and lower and top and bottom are used only for convenience of description as it is evident that the tool may be held in any position and still operate in the manner described.

I claim In a pneumatic hammer or the like, the combination with the working cylinder having a fluid-pressure inlet at an intermediate point and an exhausting port at an inter mediate point, of a separate valve casing having an exhaust port and a recessed part,

the latter being in open and constant communication with the fluid-pressure supply for the cylinder, a chambered valve seat member in open communication with the said recessed part of the casing and also having spaces respectively in communication with the lower end of the cylinder and with the cylinder exhaust port, said valve seat member also being in communication with the exhaust port of the casing and having an enlarged end chamber in communication with the cylinder through spaced ports in the latter, a ported piston operating within the cylinder, and a stepped valve mounted within the valve seat member and having end surfaces of different areas, the end surface of greater area working in said enlarged end chamber of the valve seat member, and the end surface of smaller area being exposed to the pressure within the recessed part of the casing.

In witness whereof I have hereunto set my hand in the presence of two witnesses.

FRIEDRICH ADOLF OTTO.

Witnesses:

Or'ro Kome, CHAS. J. WRIGHT. 

